Method and system for amplitude modulation utilizing a leaky wave antenna

ABSTRACT

Methods and systems for amplitude modulation using a leaky wave antenna are disclosed and may include amplitude modulating an output of one or more power amplifiers in a wireless device by modulating a bias current in the power amplifiers that are coupled to one or more leaky wave antennas. The leaky wave antennas may include a balun that may be integrated on the chip, on a package to which the chip may be affixed, and/or integrated on a printed circuit board to which the chip may be affixed. An output power of the power amplifiers may be adjusted by configuring a bias voltage on the leaky wave antennas. The bias voltage may be configured utilizing a DC to DC voltage controller. The bias current may be modulated via one or more switched current sources. The switched current sources may be binary weighted and/or may be current mirrors.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application makes reference to and claims priority to U.S.Provisional Application Ser. No. 61/246,618 filed on Sep. 29, 2009, andU.S. Provisional Application Ser. No. 61/185,245 filed on Jun. 9, 2009,each of which is hereby incorporated herein by reference in itsentirety.

This application also makes reference to:

-   U.S. patent application Ser. No. 12/650,212 filed on even date    herewith;-   U.S. patent application Ser. No. 12/650,277 filed on even date    herewith;-   U.S. patent application Ser. No. 12/650,192 filed on even date    herewith;-   U.S. patent application Ser. No. 12/650,224 filed on even date    herewith;-   U.S. patent application Ser. No. 12/650,176 filed on even date    herewith;-   U.S. patent application Ser. No. 12/650,246 filed on even date    herewith;-   U.S. patent application Ser. No. 12/650,292 filed on even date    herewith; and-   U.S. patent application Ser. No. 12/650,324 filed on even date    herewith.

Each of the above stated applications is hereby incorporated herein byreference in its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[Not Applicable]

MICROFICHE/COPYRIGHT REFERENCE

[Not Applicable]

FIELD OF THE INVENTION

Certain embodiments of the invention relate to wireless communication.More specifically, certain embodiments of the invention relate to amethod and system for amplitude modulation using a leaky wave antenna.

BACKGROUND OF THE INVENTION

Mobile communications have changed the way people communicate and mobilephones have been transformed from a luxury item to an essential part ofevery day life. The use of mobile phones is today dictated by socialsituations, rather than hampered by location or technology. While voiceconnections fulfill the basic need to communicate, and mobile voiceconnections continue to filter even further into the fabric of every daylife, the mobile Internet is the next step in the mobile communicationrevolution. The mobile Internet is poised to become a common source ofeveryday information, and easy, versatile mobile access to this datawill be taken for granted.

As the number of electronic devices enabled for wireline and/or mobilecommunications continues to increase, significant efforts exist withregard to making such devices more power efficient. For example, a largepercentage of communications devices are mobile wireless devices andthus often operate on battery power. Additionally, transmit and/orreceive circuitry within such mobile wireless devices often account fora significant portion of the power consumed within these devices.Moreover, in some conventional communication systems, transmittersand/or receivers are often power inefficient in comparison to otherblocks of the portable communication devices. Accordingly, thesetransmitters and/or receivers have a significant impact on battery lifefor these mobile wireless devices.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method for amplitude modulation using a leaky waveantenna, substantially as shown in and/or described in connection withat least one of the figures, as set forth more completely in the claims.

Various advantages, aspects and novel features of the present invention,as well as details of an illustrated embodiment thereof, will be morefully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary wireless system utilizingleaky wave antennas and enabling amplitude modulation, which may beutilized in accordance with an embodiment of the invention.

FIG. 2 is a block diagram illustrating an exemplary leaky wave antenna,in accordance with an embodiment of the invention.

FIG. 3 is a block diagram illustrating a plan view of exemplarypartially reflective surfaces, in accordance with an embodiment of theinvention.

FIG. 4 is a block diagram illustrating an exemplary phase dependence ofa leaky wave antenna, in accordance with an embodiment of the invention.

FIG. 5 is a block diagram illustrating exemplary in-phase andout-of-phase beam shapes for a leaky wave antenna, in accordance with anembodiment of the invention.

FIG. 6 is a block diagram illustrating a leaky wave antenna withvariable input impedance feed points, in accordance with an embodimentof the invention.

FIG. 7A is a block diagram of an exemplary multi-stage power amplifierutilizing a leaky wave antenna as a load and enabling amplitudemodulation, in accordance with an embodiment of the invention.

FIG. 7B is a block diagram of a current source for amplitude modulation,in accordance with an embodiment of the invention.

FIG. 8 is a block diagram illustrating amplitude modulation by anexemplary two stage power amplifier, which utilizes a leaky wave antennaas a load, in accordance with an embodiment of the invention.

FIG. 9 is a block diagram illustrating exemplary steps for amplitudemodulating a power amplifier that incorporates a leaky wave antenna, inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain aspects of the invention may be found in a method and system foramplitude modulation using a leaky wave antenna. Exemplary aspects ofthe invention may comprise amplitude modulating an output of one or morepower amplifiers in a wireless device by modulating a bias current inthe one or more power amplifiers that are coupled to one or more leakywave antennas. In this regard, an amplitude modulated signal may betransmitted from the one or more leaky wave antennas. The one or moreleaky wave antennas may comprise a balun that may be integrated on thechip, integrated on a package to which the chip may be affixed, and/orintegrated on a printed circuit board to which the chip may be affixed.An output power of the one or more power amplifiers may be adjusted byconfiguring a bias voltage on the one or more leaky wave antennas. Thebias voltage may be configured utilizing a DC to DC voltage controller.The bias current may be modulated via one or more switched currentsources. The one or more switched current sources may be binary weightedand/or may be configured as current mirrors.

FIG. 1 is a block diagram of an exemplary wireless system utilizingleaky wave antennas and enabling amplitude modulation, which may beutilized in accordance with an embodiment of the invention. Referring toFIG. 1, the wireless device 150 may comprise an antenna 151, atransceiver 152, a baseband processor 154, a processor 156, a systemmemory 158, a logic block 160, a chip 162, leaky wave antennas 164A,164B, and 164C, an external headset port 166, and a package 167. Thewireless device 150 may also comprise an analog microphone 168,integrated hands-free (IHF) stereo speakers 170, a printed circuit board171, a hearing aid compatible (HAC) coil 174, a dual digital microphone176, a vibration transducer 178, a keypad and/or touchscreen 180, and adisplay 182.

The transceiver 152 may comprise suitable logic, circuitry,interface(s), and/or code that may be enabled to modulate and upconvertbaseband signals to RF signals for transmission by one or more antennas,which may be represented generically by the antenna 151. The transceiver152 may also be enabled to downconvert and demodulate received RFsignals to baseband signals. The RF signals may be received by one ormore antennas, which may be represented generically by the antenna 151,or the leaky wave antennas 164A, 164B, and 164C. Different wirelesssystems may use different antennas for transmission and reception. Thetransceiver 152 may be enabled to execute other functions, for example,filtering the baseband and/or RF signals, and/or amplifying the basebandand/or RF signals. Although a single transceiver 152 is shown, theinvention is not so limited. Accordingly, the transceiver 152 may beimplemented as a separate transmitter and a separate receiver. Inaddition, there may be a plurality of transceivers, transmitters and/orreceivers. In this regard, the plurality of transceivers, transmittersand/or receivers may enable the wireless device 150 to handle aplurality of wireless protocols and/or standards including cellular,WLAN and PAN. Wireless technologies handled by the wireless device 150may comprise GSM, CDMA, CDMA2000, WCDMA, GMS, GPRS, EDGE, WIMAX, WLAN,3GPP, UMTS, BLUETOOTH, and ZigBee, for example.

The baseband processor 154 may comprise suitable logic, circuitry,interface(s), and/or code that may be enabled to process basebandsignals for transmission via the transceiver 152 and/or the basebandsignals received from the transceiver 152. The processor 156 may be anysuitable processor or controller such as a CPU, DSP, ARM, or any type ofintegrated circuit processor. The processor 156 may comprise suitablelogic, circuitry, and/or code that may be enabled to control theoperations of the transceiver 152 and/or the baseband processor 154. Forexample, the processor 156 may be utilized to update and/or modifyprogrammable parameters and/or values in a plurality of components,devices, and/or processing elements in the transceiver 152 and/or thebaseband processor 154. At least a portion of the programmableparameters may be stored in the system memory 158.

Control and/or data information, which may comprise the programmableparameters, may be transferred from other portions of the wirelessdevice 150, not shown in FIG. 1, to the processor 156. Similarly, theprocessor 156 may be enabled to transfer control and/or datainformation, which may include the programmable parameters, to otherportions of the wireless device 150, not shown in FIG. 1, which may bepart of the wireless device 150.

The processor 156 may utilize the received control and/or datainformation, which may comprise the programmable parameters, todetermine an operating mode of the transceiver 152. For example, theprocessor 156 may be utilized to select a specific frequency for a localoscillator, a specific gain for a variable gain amplifier, configure thelocal oscillator and/or configure the variable gain amplifier foroperation in accordance with various embodiments of the invention.Moreover, the specific frequency selected and/or parameters needed tocalculate the specific frequency, and/or the specific gain value and/orthe parameters, which may be utilized to calculate the specific gain,may be stored in the system memory 158 via the processor 156, forexample. The information stored in system memory 158 may be transferredto the transceiver 152 from the system memory 158 via the processor 156.

The system memory 158 may comprise suitable logic, circuitry,interface(s), and/or code that may be enabled to store a plurality ofcontrol and/or data information, including parameters needed tocalculate frequencies and/or gain, and/or the frequency value and/orgain value. The system memory 158 may store at least a portion of theprogrammable parameters that may be manipulated by the processor 156.

The logic block 160 may comprise suitable logic, circuitry,interface(s), and/or code that may enable controlling of variousfunctionalities of the wireless device 150. For example, the logic block160 may comprise one or more state machines that may generate signals tocontrol the transceiver 152 and/or the baseband processor 154. The logicblock 160 may also comprise registers that may hold data forcontrolling, for example, the transceiver 152 and/or the basebandprocessor 154. The logic block 160 may also generate and/or store statusinformation that may be read by, for example, the processor 156.Amplifier gains and/or filtering characteristics, for example, may becontrolled by the logic block 160.

The BT radio/processor 163 may comprise suitable circuitry, logic,interface(s), and/or code that may enable transmission and reception ofBluetooth signals. The BT radio/processor 163 may enable processingand/or handling of BT baseband signals. In this regard, the BTradio/processor 163 may process or handle BT signals received and/or BTsignals transmitted via a wireless communication medium. The BTradio/processor 163 may also provide control and/or feedback informationto/from the baseband processor 154 and/or the processor 156, based oninformation from the processed BT signals. The BT radio/processor 163may communicate information and/or data from the processed BT signals tothe processor 156 and/or to the system memory 158. Moreover, the BTradio/processor 163 may receive information from the processor 156and/or the system memory 158, which may be processed and transmitted viathe wireless communication medium a Bluetooth headset, for example

The CODEC 172 may comprise suitable circuitry, logic, interface(s),and/or code that may process audio signals received from and/orcommunicated to input/output devices. The input devices may be within orcommunicatively coupled to the wireless device 150, and may comprise theanalog microphone 168, the stereo speakers 170, the hearing aidcompatible (HAC) coil 174, the dual digital microphone 176, and thevibration transducer 178, for example. The CODEC 172 may be operable toup-convert and/or down-convert signal frequencies to desired frequenciesfor processing and/or transmission via an output device. The CODEC 172may enable utilizing a plurality of digital audio inputs, such as 16 or18-bit inputs, for example. The CODEC 172 may also enable utilizing aplurality of data sampling rate inputs. For example, the CODEC 172 mayaccept digital audio signals at sampling rates such as 8 kHz, 11.025kHz, 12 kHz, 16 kHz, 22.05 kHz, 24 kHz, 32 kHz, 44.1 kHz, and/or 48 kHz.The CODEC 172 may also support mixing of a plurality of audio sources.For example, the CODEC 172 may support audio sources such as generalaudio, polyphonic ringer, I²S FM audio, vibration driving signals, andvoice. In this regard, the general audio and polyphonic ringer sourcesmay support the plurality of sampling rates that the audio CODEC 172 isenabled to accept, while the voice source may support a portion of theplurality of sampling rates, such as 8 kHz and 16 kHz, for example.

The chip 162 may comprise an integrated circuit with multiple functionalblocks integrated within, such as the transceiver 152, the processor156, the baseband processor 154, the BT radio/processor 163, the CODEC172, and the leaky wave antenna 164A. The number of functional blocksintegrated in the chip 162 is not limited to the number shown in FIG. 1.Accordingly, any number of blocks may be integrated on the chip 162depending on chip space and wireless device 150 requirements, forexample.

The leaky wave antennas 164A, 164B, and 164C may comprise a resonantcavity with a highly reflective surface and a lower reflectivitysurface, and may be integrated in and/or on the chip 162, the package167, and/or the printed circuit board 171. The reduced reflectivitysurface may allow the resonant mode to “leak” out of the cavity. Thelower reflectivity surface of the leaky wave antennas 164A, 1648, and164C may be configured with slots in a metal surface, or a pattern ofmetal patches, as described further in FIGS. 2 and 3. The physicaldimensions of the leaky wave antennas 164A, 164B, and 164C may beconfigured to optimize bandwidth of transmission and/or the beam patternradiated. In another embodiment of the invention, the leaky wave antenna164B may be integrated on the package 167, and the leaky wave antenna164C may be integrated in and/or on the printed circuit board 171 towhich the chip 162 may be affixed. In this manner, the dimensions of theleaky wave antennas 164B and 164C may not be limited by the size of thechip 162.

In an exemplary embodiment of the invention, the leaky wave antennas164A, 164B, and/or 164C may enable the amplitude modulation of poweramplifiers in the wireless device 150. For example, a bias voltageapplied to the antennas 164A, 164B, and/or 164C may be modulated therebymodulating the amplitude of the transmitted signal.

The external headset port 166 may comprise a physical connection for anexternal headset to be communicatively coupled to the wireless device150. The analog microphone 168 may comprise suitable circuitry, logic,interface(s), and/or code that may detect sound waves and convert themto electrical signals via a piezoelectric effect, for example. Theelectrical signals generated by the analog microphone 168 may compriseanalog signals that may require analog to digital conversion beforeprocessing.

The package 167 may comprise a ceramic package, a printed circuit board,or other support structure for the chip 162 and other components of thewireless device 150. In this regard, the chip 162 may be bonded to thepackage 167. The package 167 may comprise insulating and conductivematerial, for example, and may provide isolation between electricalcomponents mounted on the package 167.

The stereo speakers 170 may comprise a pair of speakers that may beoperable to generate audio signals from electrical signals received fromthe CODEC 172. The HAC coil 174 may comprise suitable circuitry, logic,and/or code that may enable communication between the wireless device150 and a T-coil in a hearing aid, for example. In this manner,electrical audio signals may be communicated to a user that utilizes ahearing aid, without the need for generating sound signals via aspeaker, such as the stereo speakers 170, and converting the generatedsound signals back to electrical signals in a hearing aid, andsubsequently back into amplified sound signals in the user's ear, forexample.

The dual digital microphone 176 may comprise suitable circuitry, logic,interface(s), and/or code that may be operable to detect sound waves andconvert them to electrical signals. The electrical signals generated bythe dual digital microphone 176 may comprise digital signals, and thusmay not require analog to digital conversion prior to digital processingin the CODEC 172. The dual digital microphone 176 may enable beamformingcapabilities, for example.

The vibration transducer 178 may comprise suitable circuitry, logic,interface(s), and/or code that may enable notification of an incomingcall, alerts and/or message to the wireless device 150 without the useof sound. The vibration transducer may generate vibrations that may bein synch with, for example, audio signals such as speech or music.

In operation, control and/or data information, which may comprise theprogrammable parameters, may be transferred from other portions of thewireless device 150, not shown in FIG. 1, to the processor 156.Similarly, the processor 156 may be enabled to transfer control and/ordata information, which may include the programmable parameters, toother portions of the wireless device 150, not shown in FIG. 1, whichmay be part of the wireless device 150.

The processor 156 may utilize the received control and/or datainformation, which may comprise the programmable parameters, todetermine an operating mode of the transceiver 152. For example, theprocessor 156 may be utilized to select a specific frequency for a localoscillator, a specific gain for a variable gain amplifier, configure thelocal oscillator and/or configure the variable gain amplifier foroperation in accordance with various embodiments of the invention.Moreover, the specific frequency selected and/or parameters needed tocalculate the specific frequency, and/or the specific gain value and/orthe parameters, which may be utilized to calculate the specific gain,may be stored in the system memory 158 via the processor 156, forexample. The information stored in system memory 158 may be transferredto the transceiver 152 from the system memory 158 via the processor 156.

The CODEC 172 in the wireless device 150 may communicate with theprocessor 156 in order to transfer audio data and control signals.Control registers for the CODEC 172 may reside within the processor 156.The processor 156 may exchange audio signals and control information viathe system memory 158. The CODEC 172 may up-convert and/or down-convertthe frequencies of multiple audio sources for processing at a desiredsampling rate.

The wireless signals may be transmitted and received by the leaky waveantennas 164A, 164B, and 164C. The beam pattern radiated from the leakywave antennas 164A, 164B, and 164C may be configured by adjusting thefrequency of the signal communicated to the leaky wave antennas 164A,164B, and 164C. Furthermore, the physical characteristics of the leakywave antennas 164A, 1648, and 164C may be configured to adjust thebandwidth of the transmitted signal.

In an embodiment of the invention, the power amplifiers in thetransceiver 152 may be operable to provide amplitude modulation bymodulating the bias current in one or more stages of the poweramplifiers. In addition, the bias voltage for the power amplifiersapplied to the leaky wave antennas 164A, 164B, and/or 164C may be scaledto improve efficiency. In this manner, linear amplitude modulation, highpower control dynamic range and high output power may be achieved.

FIG. 2 is a block diagram illustrating an exemplary leaky wave antenna,in accordance with an embodiment of the invention. Referring to FIG. 2,there is shown the leaky wave antenna 164A, 164B, and/or 164C comprisinga partially reflective surface 201A, a reflective surface 201B, and afeed point 203. The space between the partially reflective surface 201Aand the reflective surface 201B may be filled with dielectric material,for example, and the height, h, between the partially reflective surface201A and the reflective surface 201B may be utilized to configure thefrequency of transmission of the leaky wave antenna 164A, 164B, and/or164C.

The feed point 203 may comprise a input terminal for applying an inputvoltage to the leaky wave antenna 164A, 164B, and/or 164C. The inventionis not limited to a single feed point 203, as there may be any amount offeed points for different phases of signal, for example, to be appliedto the leaky wave antenna 164A, 164B, and/or 164C.

In an embodiment of the invention, the height, h, may be one-half thewavelength of the transmitted mode from the leaky wave antenna 164A,164B, and/or 164C. In this manner, the phase of an electromagnetic modethat traverses the cavity twice may be coherent with the input signal atthe feed point 203, thereby configuring a resonant cavity known as aFabry-Perot cavity. The magnitude of the resonant mode may decayexponentially in the lateral direction from the feed point 203, therebyreducing or eliminating the need for confinement structures to the sidesof the leaky wave antenna 164A, 164B, and/or 164C. The input impedanceof the leaky wave antenna 164A, 164B, and/or 164C may be configured bythe vertical placement of the feed point 203, as described further inFIG. 6.

In operation, a signal to be transmitted via a power amplifier may becommunicated to the feed point 203 of the leaky wave antenna 164A, 164B,and/or 164C with a frequency f. The cavity height, h, may be configuredto correlate to one half the wavelength of the signal of frequency f.The signal may traverse the height of the cavity and may be reflected bythe partially reflective surface 201A, and then traverse the height backto the reflective surface 201B. Since the wave will have travelled adistance corresponding to a full wavelength, constructive interferencemay result and a resonant mode may thereby be established.

Leaky wave antennas may enable the configuration of high gain antennaswithout the need for a large array of antennas which require a complexfeed network and suffer from loss due to feed lines. The leaky waveantenna 164A, 164B, and/or 164C may be integrated on or in a chip,package, or printed circuit board. The leaky wave antenna 164A, 164B,and/or 164C may comprise a load on a power amplifier. The inputimpedance of the leaky wave antenna 164A, 164B, and/or 164C may beconfigured to match the output impedance of the power amplifier. In thismanner, matching circuit requirements may be reduced or eliminated.

In an exemplary embodiment of the invention, the leaky wave antennas164A, 164B, and/or 164C may enable the amplitude modulation of poweramplifiers in the wireless device 150. For example, a bias voltageapplied to the antennas 164A, 164B, and/or 164C may be modulated therebymodulating the amplitude of the transmitted signal.

The beam shape of the transmitted may comprise a narrow vertical beamwhen the frequency of the signal communicated to the feed point 203matches the resonant frequency of the cavity. In instances where thefrequency shifts from the center frequency, the beam shape may becomeconical, with nodes at an angle from vertical. This is described furtherwith respect to FIGS. 4 and 5.

In an embodiment of the invention, the leaky wave antennas 164A, 164B,and/or 164C may be configured as a balun with a bias voltage, VDD, whichmay be utilized to control the output voltage swing of a poweramplifier. In addition, amplitude modulation in the power amplifier maybe enabled by controlling the bias current. In this manner, linearamplitude modulation, high power control dynamic range and high outputpower may be achieved.

FIG. 3 is a block diagram illustrating a plan view of exemplarypartially reflective surfaces, in accordance with an embodiment of theinvention. Referring to

FIG. 3, there is shown a partially reflective surface 300 comprisingperiodic slots in a metal surface, and a partially reflective surface320 comprising periodic metal patches. The partially reflective surfaces300/320 may comprise different embodiments of the partially reflectivesurface 201A described with respect to FIG. 2.

The spacing, dimensions, shape, and orientation of the slots and/orpatches in the partially reflective surfaces 300/320 may be utilized toconfigure the bandwidth, and thus Q-factor, of the resonant cavitydefined by the partially reflective surfaces 300/320 and a reflectivesurface, such as the reflective surface 201B, described with respect toFIG. 2. The partially reflective surfaces 300/320 may thus comprisefrequency selective surfaces due to the narrow bandwidth of signals thatmay leak out of the structure as configured by the slots and/or patches.

The spacing between the patches and/or slots may be related towavelength of the signal transmitted and/or received, which may besomewhat similar to beamforming with multiple antennas. The length ofthe slots and/or patches may be several times larger than the wavelengthof the transmitted and/or received signal or less, for example, sincethe leakage from the slots and/or regions surround the patches may addup, similar to beamforming with multiple antennas.

In an embodiment of the invention, the slots/patches may be configuredvia micro-electromechanical system (MEMS) switches to tune the Q of theresonant cavity.

FIG. 4 is a block diagram illustrating an exemplary phase dependence ofa leaky wave antenna, in accordance with an embodiment of the invention.Referring to FIG. 4, there is shown a leaky wave antenna comprising thepartial reflective surface 201A, the reflective surface 201B, and thefeed point 203. In-phase condition 400 illustrates the relative beamshape transmitted by the leaky wave antenna 164A, 164B, and/or 164C whenthe frequency of the signal communicated to the feed point 203 matchesthat of the resonant cavity as defined by the cavity height h and thedielectric constant of the material between the reflective surfaces.

Similarly, the out-of-phase condition 420 illustrates the relative beamshape transmitted by the leaky wave antenna 164A, 164B, and/or 164C whenthe frequency of the signal communicated to the feed point 203 does notmatch that of the resonant cavity. The resulting beam shape may beconical, as opposed to a single main vertical node. These areillustrated further with respect to FIG. 5.

FIG. 5 is a block diagram illustrating exemplary in-phase andout-of-phase beam shapes for a leaky wave antenna, in accordance with anembodiment of the invention. Referring to FIG. 5, there is shown a plot500 of transmitted signal beam shape versus angle for the in-phase andout-of-phase conditions for a leaky wave antenna.

The In-phase curve in the plot 500 may correlate to the case where thefrequency of the signal communicated to a leaky wave antenna matches theresonant frequency of the cavity. In this manner, a single vertical mainnode may result. In instances where the frequency of the signal at thefeed point is not at the resonant frequency, a double, or conical-shapednode may be generated as shown by the Out-of-phase curve in the plot500.

FIG. 6 is a block diagram illustrating a leaky wave antenna withvariable input impedance feed points, in accordance with an embodimentof the invention. Referring to FIG. 6, there is shown a leaky waveantenna 600 comprising the partially reflective surface 201A and thereflective surface 201B. There is also shown feed points 601A-601C. Thefeed points 601A-601C may be located at different positions along theheight, h, of the cavity thereby configuring different impedance pointsfor the leaky wave antenna.

In this manner, a leaky wave antenna may be operable to couple to poweramplifiers with different output impedances thereby increasing couplingefficiency without requiring impedance matching circuits. Higherimpedance PAs may be coupled to feed points placed higher in the cavityand lower impedance PAs may be coupled to feed points placed closer tothe reflective surface 201B.

FIG. 7A is a block diagram of an exemplary multi-stage power amplifierutilizing a leaky wave antenna as a load and enabling amplitudemodulation, in accordance with an embodiment of the invention. Referringto FIG. 7A, there is shown a power amplifier (PA) 700 comprising theCMOS transistors M1-M6, current sources 701A-701C, a notch filter 703,switches S1-S6, a balun 705, and a DC-to-DC controller 707. There isalso shown input signals LO+ and LO−, an amplitude modulation signal AM,a power control signal, PC, and a control signal, Control, communicatedto the DC-to-DC controller 607.

The current sources 701A may comprise suitable circuitry, logic,interfaces, and/or code that may be operable to provide bias currents tothe various stages of the PA 700. The current sources 701A-701C maycomprise one or more CMOS transistors of varying size and thus currentflow for a given gate and drain-source voltages. In an embodiment of theinvention, the current source 701B may supply a current eight timeshigher than the current source 701A, and the current source 701C maysupply a current eight times higher than the current source 701B. Inanother embodiment of the invention, the current sources 701A-701C maybe binary weighted where each current source supplies double or half thecurrent of an adjacent current source.

The transistors M1-M6 may comprise the various gain stages of the PA700, and may be configured to operate in differential mode or commonmode. The switches S1-S6 may be operable to configure the input stages,comprising the gate terminals of the transistors M1-M6, to operate indifferential mode or common mode. In differential mode, both switches ina transistor pair, switches S1 and S2 for CMOS transistors M1 and M2,for example, may be switched to the LO+ and LO− input signals.Similarly, switch S2 may be switched to ground, and switch S1 may becoupled to the LO+ input signal, thereby configuring the M1/M2 stage incommon mode.

The number of stages in the PA 700 is not limited to the number shown inFIG. 7A. Accordingly, any number of stages may be utilized depending onchip space and power requirements, for example.

The notch filter 703 may comprise suitable circuitry, logic, interfaces,and/or code that may be operable to filter out signals in a narrowfrequency band while allowing signals to pass through that are outsidethat frequency band.

The balun 705 may comprise suitable circuitry, logic, interfaces, and/orcode that may be operable to convert a balanced signal to an unbalancedsignal. The output of the balun 705 may be communicatively coupled to aleaky wave antenna as a load for the balun 705 and the PA 700. Inanother embodiment of the invention, the balun 705 may comprise a leakywave antenna with multiple input feed points to enable reception ofbalanced signals.

In operation, a local oscillator signal comprising LO+ and LO− may becommunicated to the gain stages comprising the CMOS transistor pairsM1/M2, M3/M4, and M5/M6. The switches S1-S6 may be utilized to configurethe PA stages in differential or common mode. Amplitude modulation maybe applied via the AM signal that may be operable to modulate thecurrent sources 701A-701C, thereby modulating the output signalamplitude of the PA 700. In addition, the power output may be configuredutilizing the DC-to-DC controller 707 via the Control signal. In thismanner, the maximum voltage swing of the signal communicated to anantenna may be configured.

In an embodiment of the invention, the balun 705 may communicate thebalanced signal generated by the PA 700 as an unbalanced signal to anantenna coupled to the balun 705. In another embodiment of theinvention, the balun 705 may comprise a leaky wave antenna, therebyenabling the reception of balanced signals to be transmitted by theleaky wave antenna configured as a balun. The balun 705 may then alsocomprise a load for the PA 700 which may be configured for a desiredimpedance for proper matching. In this manner, a conventional tunedcircuit, matching circuit, and antenna may be replaced by a leaky waveantenna on a PA.

In an embodiment of the invention, amplitude modulation may be enabledby applying an AM signal to the current sources 701A-701C. In addition,a power control signal, PC, may be applied to the current sources in701A-701C. This is described further with respect to FIG. 7B. The AMsignal may cause the current flow through the transistors M1-M6 tomodulate, thereby modulating the amplitude of the signal transmitted bythe leaky wave antenna.

In instances of non-linear amplification, the bias voltage generated bythe DC-to-DC controller 707 via the Control signal may provide amplitudemodulation, but in linear amplification, the current source 701A-701Cmay be set digitally via the power control signal, PC, with anadditional analog signal, AM, to modulate current sources 701A-701C,thereby enabling amplitude modulation. Utilizing the bias voltage on theleaky wave antenna may increase the efficiency of transmission.

FIG. 7B is a block diagram of a current source for amplitude modulation,in accordance with an embodiment of the invention. Referring to FIG. 7B,there is shown a current source 730 comprising transistorsM_(AM1)-M_(AM4) and switches S7 and S8. There is also shown a biasvoltage VB, switching signals B_(K) and B′_(K), a current I, and theamplitude modulation signal AM. The switching signals B_(K) and B′_(K)may comprise the power control signal PC described in FIG. 7B, whereB_(K) is the complement of B′_(K).

The current source 730 may comprise a current mirror that may beoperable to modulate the current I at a magnitude proportional to theamplitude modulation signal, AM. The proportionality may be configuredby the size ratio of the CMOS transistors M_(AM1) and M_(AM2). In thismanner, each of the current sources 701A-710C may have different ratios,thereby enabling a wide range of current available to the PA 700,described with respect to FIG. 7A.

The switches S7 and S8 may be operable to switch the gate terminals ofthe transistors M_(AM3) and M_(AM4) between ground and the drainterminal of the PMOS transistor MAM2.

In operation, the amplitude signal AM may be communicated to the gateterminals of the PMOS transistors M_(AM1) and M_(AM2). The modulation ofthe gate voltage of M_(AM2) may result in a modulated current fromsource to drain of PMOS transistor M_(AM2) when switch S7 is closed andswitch S8 is open. This modulating current may then modulate the gatevoltage of the NMOS transistors M_(AM3) and M_(AM4), which may result inthe modulation of the current I at a magnitude that may be the magnitudeof the AM signal times a proportionality factor defined by the PMOStransistors M_(AM1) and M_(AM2).

In instances where the switch S7 is open and switch S8 is closed, thegate terminals of M_(AM3) and M_(AM4) may be at ground thereby turningoff the transistors M_(AM3) and M_(AM4) which may result in the currentI approaching zero.

FIG. 8 is a block diagram illustrating amplitude modulation by anexemplary two stage power amplifier, which utilizes a leaky wave antennaas a load, in accordance with an embodiment of the invention. Referringto FIG. 8, there is shown a power amplifier 800 comprising thetransistors M_(INP), M_(INN), MCP, MCN, M2N, and M2P, the bias circuit810, resistors R_(L), R1, and R2, capacitors C1-C6, and inductorsLL1-LL4, Ls, and L_(M1)-L_(M2). There is also shown the input terminalsINP and INN, output terminals OutP and OutN, a bias voltage VDC, a biasvoltage V, and the bias control input Bias.

The bias circuit 810 may comprise CMOS transistors MB1-MB8 and a currentsource 801. The current source 801 may comprise suitable circuitry,logic, interfaces, and/or code that may be operable to supply a currentto the CMOS transistors MB1-MB8. The Bias control input and the biasvoltage V may be utilized to configure the bias current for the PA 800.

The transistors M_(INP), M_(INN), MCP, MCN, M2N, the inductors LL1 andLL2, and the resistor RL may comprise the first stage of the PA 800 andmay comprise a cascode stage. The input to the first stage may comprisethe INP and INN input terminals, and the output signal may becommunicated to the second stage via the coupling capacitors C1 and C2.The second stage of the PA 800 may comprise the transistors M2N and M2P,and the inductors Ls, LL3, and LL4.

In a conventional PA, the second stage of the PA 800 may comprisediscrete inductors LL3 and LL4 as loads for the PA and a matchingcircuit comprising capacitors C3-C6 and inductors LM1 and LM2, which maybe communicated to an antenna. In an embodiment of the invention, theload inductors LL3 and LL4, the matching circuitry, and antenna may bereplaced by a leaky wave antenna. The leaky wave antenna may provide thetuned circuit via the resonant frequency of the resonant cavity, and mayprovide an impedance matched to the PA 800 for increased couplingefficiency.

In operation, an input signal may be communicated to the INP and INNinput terminals for amplification by the first and second stages of thePA 800. The bias conditions for the PA 800 may be configured via theBias and V signals. In an embodiment of the invention, the loadinductors LL3 and LL4 may comprise one or more leaky wave antennas thatmay be impedance matched to the PA 800, thereby eliminating the need forthe matching circuitry comprising the capacitors C3-C6 and inductors LM1and LM2.

The inductors LL3 and LL4 that may comprise leaky wave antennas maytransmit the amplified signal in a direction defined by the geometry ofthe leaky wave antenna as described with respect to FIGS. 2-5. The PA800 may be operable to provide amplitude modulation by modulating thebias current in the two gain stages. In addition, the bias voltage VDCmay be adjusted to tune output power while improving efficiency.

FIG. 9 is a block diagram illustrating exemplary steps for amplitudemodulating a power amplifier that incorporates a leaky wave antenna, inaccordance with an embodiment of the invention. Referring to FIG. 9, instep 903 after start step 901, the leaky wave antenna may be configuredas a load on the PA enabling transmission at a desired frequency. Instep 905, the gain of the PA may be configured to a desired level. Instep 907, an amplitude modulation signal may be configured to modulatethe output signal of the PA by modulating a bias current in the PA.Additionally, the output power of the PA may be modulated by tuning abias voltage of the PA. If, in step 909, the wireless device 150 is tobe powered down, the exemplary steps may proceed to end step 911.However, if the wireless device 150 is not to be powered down, theexemplary steps may proceed to step 903 to configure the leaky waveantenna.

In an embodiment of the invention, a method and system are disclosed foramplitude modulating an output of one or more power amplifiers 700/800in a wireless device 150 by modulating a bias current in the one or morepower amplifiers 700/800 that are coupled to one or more leaky waveantennas 164A, 164B, and/or 164C. In this regard, an amplitude modulatedsignal may be transmitted from the one or more leaky wave antennas 164Aand/or 164B. The one or more leaky wave antennas 164A, 164B, and/or 164Cmay comprise a balun 705 that may be integrated on the chip 162,integrated on a package 167 to which the chip 162 may be affixed, and/orintegrated on a printed circuit board 171 to which the chip 162 may beaffixed. An output power of the one or more power amplifiers 700/800 maybe adjusted by configuring a bias voltage on the one or more leaky waveantennas 164A, 164B, and/or 164C. The bias voltage may be configuredutilizing a DC to DC voltage controller 707. The bias current may bemodulated via one or more switched current sources 701A-701C/730. Theone or more switched current sources 701A-701C/730 may be binaryweighted and/or may be current mirrors.

Another embodiment of the invention may provide a machine and/orcomputer readable storage and/or medium, having stored thereon, amachine code and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for amplitudemodulation using a leaky wave antenna.

Accordingly, aspects of the invention may be realized in hardware,software, firmware or a combination thereof. The invention may berealized in a centralized fashion in at least one computer system or ina distributed fashion where different elements are spread across severalinterconnected computer systems. Any kind of computer system or otherapparatus adapted for carrying out the methods described herein issuited. A typical combination of hardware, software and firmware may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

One embodiment of the present invention may be implemented as a boardlevel product, as a single chip, application specific integrated circuit(ASIC), or with varying levels integrated on a single chip with otherportions of the system as separate components. The degree of integrationof the system will primarily be determined by speed and costconsiderations. Because of the sophisticated nature of modernprocessors, it is possible to utilize a commercially availableprocessor, which may be implemented external to an ASIC implementationof the present system. Alternatively, if the processor is available asan ASIC core or logic block, then the commercially available processormay be implemented as part of an ASIC device with various functionsimplemented as firmware.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext may mean, for example, any expression, in any language, code ornotation, of a set of instructions intended to cause a system having aninformation processing capability to perform a particular functioneither directly or after either or both of the following: a) conversionto another language, code or notation; b) reproduction in a differentmaterial form. However, other meanings of computer program within theunderstanding of those skilled in the art are also contemplated by thepresent invention.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiments disclosed, but that the present inventionwill include all embodiments falling within the scope of the appendedclaims.

What is claimed is:
 1. A method for communication, the methodcomprising: performing using one or more circuits in a wireless device,said one or more circuits comprising one or more power amplifiers on achip, wherein said one or more power amplifiers are coupled to one ormore leaky wave antennas without using matching circuitry for said oneor more power amplifiers: modulating a bias current in said one or morepower amplifiers; and amplitude modulating an output of said one or morepower amplifiers utilizing said modulated bias current.
 2. The methodaccording to claim 1, wherein said one or more leaky wave antennascomprise a balun.
 3. The method according to claim 1, wherein said oneor more leaky wave antennas are integrated on said chip.
 4. The methodaccording to claim 1, wherein said one or more leaky wave antennas areintegrated on a package to which said chip is affixed.
 5. The methodaccording to claim 1, wherein said one or more leaky wave antennas areintegrated on a printed circuit board to which said chip is affixed. 6.The method according to claim 1, comprising adjusting an output power ofsaid one or more power amplifiers by configuring a bias voltage on saidone or more leaky wave antennas.
 7. The method according to claim 6,comprising configuring said bias voltage utilizing a DC to DC voltagecontroller.
 8. The method according to claim 1, comprising modulatingsaid bias current via one or more switched current sources.
 9. Themethod according to claim 8, wherein said one or more switched currentsources are binary weighted.
 10. The method according to claim 8,wherein said one or more switched current sources are current mirrors.11. A system for enabling communication, the system comprising: one ormore or more circuits in a wireless device, said one or more circuitscomprising one or more power amplifiers on a chip, said one or morepower amplifiers are coupled to one or more leaky wave antennas withoutusing matching circuitry for said one or more power amplifiers, whereinsaid one or more or more circuits are operable to: modulate a biascurrent in said one or more power amplifiers; and amplitude modulate anoutput of said one or more power amplifiers utilizing said modulatedbias current.
 12. The system according to claim 11, wherein said one ormore leaky wave antennas comprise a balun.
 13. The system according toclaim 11, wherein said one or more leaky wave antennas are integrated onsaid chip.
 14. The system according to claim 11, wherein said one ormore leaky wave antennas are integrated on a package to which said chipis affixed.
 15. The system according to claim 11, wherein said one ormore leaky wave antennas are integrated on a printed circuit board towhich said chip is affixed.
 16. The system according to claim 11,wherein said one or more circuits are operable to adjust an output powerof said one or more power amplifiers by configuring a bias voltage onsaid one or more leaky wave antennas.
 17. The system according to claim16, wherein said one or more circuits are operable to configure saidbias voltage utilizing a DC to DC voltage controller.
 18. The systemaccording to claim 11, wherein said one or more circuits are operable tomodulate said bias current via one or more switched current sources. 19.The system according to claim 18, wherein said one or more switchedcurrent sources are binary weighted.
 20. The system according to claim18, wherein said one or more switched current sources are currentmirrors.